Non-aqueous electrolytic solution for lithium secondary battery and lithium secondary battery using the same

ABSTRACT

A non-aqueous electrolytic solution is advantageously used in preparation of a lithium secondary battery excellent in cycle characteristics. In the non-aqueous electrolytic solution for a lithium secondary battery, an electrolyte salt is dissolved in a non-aqueous solvent. The non-aqueous electrolytic solution further contains a vinylene carbonate compound in an amount of 0.01 to 10 wt. %, and an alkyne compound in an amount of 0.01 to 10 wt. %.

FIELD OF THE INVENTION

The present invention relates to a lithium secondary battery showingexcellent cycle characteristics, and a non-aqueous electrolytic solutionadvantageously used in preparation of the lithium secondary batteryexcellent in cycle characteristics.

BACKGROUND OF THE INVENTION

The lithium secondary battery has recently been widely used for example,as an electric source for driving small-sized electronics. The lithiumsecondary battery has a basic structure comprising a positiveelectriode, a negative electrode and a non-aqueous electrolyticsolution, which are contained in a sealed cell. The positive electrodepreferably comprises a complex oxide of lithium such as LiCoO₂, and thenegative electrode preferably comprises a carbon material or metalliclithium. A carbonate such as ethylene carbonate (EC) or propylenecarbonate (PC) has been advantageously used in the non-aqueouselectrolytic solution for the lithium secondary battery.

The recent lithium secondary battery requires a further improvement onbattery performance such as cycle characteristics of the battery andelectric capacity.

In a lithium secondary battery, a complex oxide of lithium such asLiCoO₂, LiMn₂O₄ and LiNiO₂ is often used as a positive electrodematerial. A process of recharging the battery causes a local oxidationand decomposition reaction of a part of a solvent contained in anon-aqueous electrolytic solution. A decomposition product inhibits anordinary electrochemical reaction of the battery to lower batteryperformance. The reason is considered that a solvent iselectrochemically oxidized along an interface between the positiveelectrode material and the non-aqueous electrolytic solution.

In a lithium secondary battery, a highly crystallized carbon materialsuch as natural or artificial graphite is often used as a negativeelectrode material. A process of recharging the battery causes a localreduction and decomposition reaction of a part of a solvent contained ina non-aqueous electrolytic solution. Ethylene carbonate (EC) is widelyused as a solvent of the non-aqueous electrolytic solvent. Ethylenecarbonate may particularly be reduced and decomposed to lower batteryperformance while repeating charge and discharge.

Japanese Patent Provisional Publication No. 8 (1996)-45545 and U.S. Pat.No. 5,626,981 recommend adding a vinylene carbonate compound to anon-aqueous electrolytic solution to improve battery performance of thelithium secondary battery. It is further reported that the cycle life islengthened using the electric solution containing the vinylene carbonatecompound.

Japanese Patent Provisional Publication Nos. 2000-195545, 2001-313072,2002-100399 and 2002-124297 and U.S. Pat. No. 6,479,191 B1 recommendadding an alkyne compound to a non-aqueous electrolytic solution toimprove battery performance of the lithium secondary battery. It isfurther reported that the cycle life is lengthened using the electricsolution containing the alkyne compound.

Increase in density of a positive electrode composition layer or anegative electrode composition layer has recently been examined toenlarge capacity of the lithium secondary battery. Japanese PatentProvisional Publication No. 2003-142075 describes a lithium secondarybattery comprising a positive electrode composition layer having adensity of 3.3 to 3.7 g/cm³ provided on aluminum foil, and a negativeelectrode composition layer having a density of 1.4 to 1.8 g/cm³provided on copper foil. It is further reported that the obtainedlithium secondary battery has high energy density and high safety, andcan be preserved at an elevated temperature.

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention

As is described in the above-mentioned documents, battery performancesuch as cycle characteristics can be improved by adding a vinylenecarbonate compound or an alkyne compound to a non-aqueous electrolyticsolution of a lithium secondary battery.

The conventional lithium secondary battery comprises positive electrodeand negative electrode composition layers of relatively low density. Thebattery performance such as the cycle characteristics can be improved byadding a vinylene carbonate compound or an alkyne cornpound to anon-aqueous electrolytic solution of the conventional lithium secondarybattery.

On the other hand, the recent lithium secondary battery comprisespositive electrode and negative electrode composition layers of highdensity. The present inventors have found that cycle characteristics arescarcely improved by adding the above-mentioned additive to thenon-aqueous electrolytic solution of the recent lithium secondarybattery. The inventors have further found that the electrolytic solutionis decomposed in the battery to cause shortage (dry up) of theelectrolytic solution. The cycle characteristics mean a feature ofkeeping a high charge capacity after repeating charge and dischargeoperations many times.

An object of the present invention is to provide a non-aqueouselectrolytic solution that has solved the above-mentioned problems ofthe non-aqueous electrolytic solution for the lithium secondary battery.

Means to Solve the Problem

The present invention provides a non-aqueous electrolytic solution for alithium secondary battery in which an electrolyte salt is dissolved in anon-aqueous solvent, wherein the non-aqueous electrolytic solutionfurther contains a vinylene carbonate compound represented by theformula (I) in an amount of 0.01 to 10 wt. %, and an alkyne compoundrepresented by the formula (II), (III), (IV), (V), (VI) or (VII) in anamount of 0.01 to 10 wt. %:

(in which each of R¹ and R² independently is a hydrogen atom or an alkylgroup having 1 to 4 carbon atoms)

(in which each of R³ to R⁵ independently is a hydrogen atom, an alkylgroup having 1 to 12 carbon atoms, a cycloalkyl group having 3 to 6carbon atoms or an aryl group having 6 to 12 carbon atoms, or R⁴ and R⁵are combined with each other to form a cycloalkylene group having 3 to 6carbon atoms; x is 1 or 2; and Y¹ is —COOR²⁰, —COR²⁰ or —SO₂R²⁰, whereinR²⁰ is a hydrogen atom, an alkyl group having 1 to 12 carbon atoms, acycloalkyl group having 3 to 6 carbon atoms or an aryl group having 6 to12 carbon atoms)

(in which each of R⁶ to R⁹ independently is a hydrogen atom, an alkylgroup having 1 to 12 carbon atoms, a cycloalkyl group having 3 to 6carbon atoms or an aryl group having 6 to 12 carbon atoms, or R⁶ and R⁷or R⁸ and R⁹ are combined with each other to form a cycloalkylene grouphaving 3 to 6 carbon atoms; x is 1 or 2; Y² is —COOR²¹, —COR²¹ or—SO₂R²¹, wherein R²¹ is a hydrogen atom, an alkyl group having 1 to 12carbon atoms, a cycloalkyl group having 3 to 6 carbon atoms or an arylgroup having 6 to 12 carbon atoms; and Y³is —COOR²², —COR²² or —SO₂R²², wherein R²² is a hydrogen atom, an alkylgroup having 1 to 12 carbon atoms, a cycloalkyl group having 3 to 6carbon atoms or an aryl group having 6 to 12 carbon atoms)

(in which each of R¹⁰ to R¹³ independently is a hydrogen atom, an alkylgroup having 1 to 12 carbon atoms, a cycloalkyl group having 3 to 6carbon atoms or an aryl group having 6 to 12 carbon atoms, or R¹⁰ andR¹¹ or R¹² and R¹³ are combined with each other to form a cycloalkylenegroup having 3 to 6 carbon atoms; x is 1 or 2; Y⁴ is —COOR²³, —COR²³ or—SO₂R²³, wherein R²³ is a hydrogen atom, an alkyl group having 1 to 12carbon atoms, a cycloalkyl group having 3 to 6 carbon atoms or an arylgroup having 6 to 12 carbon atoms; and Y⁵ is —COOR²⁴, —COR²⁴ or —SO₂R²⁴,wherein R²⁴ is a hydrogen atom, an alkyl group having 1 to 12 carbonatoms, a cycloalkyl group having 3 to 6 carbon atoms or an aryl grouphaving 6 to 12 carbon atoms)

(in which each of R¹⁴ to R¹⁹ independently is a hydrogen atom, an alkylgroup having 1 to 12 carbon atoms, a cycloalkyl group having 3 to 6carbon atoms or an aryl group having 6 to 12 carbon atoms, or R¹⁵ andR¹⁶ or R¹⁷ and R¹⁸ are combined with each other to form a cycloalkylenegroup having 3 to 6 carbon atoms; and x is 1 or 2)

(in which each of R²⁵ to R²⁷ independently is a hydrogen atom, an alkylgroup having 1 to 12 carbon atoms, a cycloalkyl group having 3 to 6carbon atoms, an aryl group having 6 to 12 carbon atoms or an aralkylgroup having 7 to 12 carbon atoms, or R²⁶ and R²⁷ are combined with eachother to form a cycloalkylene group having 3 to 6 carbon atoms; x is 1or 2; W is sulfinyl, sulfonyl or oxalyl; and Y⁶ is an alkyl group having1 to 12 carbon atoms, an alkenyl group having 2 to 12 carbon atoms, analkynyl group having 2 to 12 carbon atoms, a cycloalkyl group having 3to 6 carbon atoms, an aryl group having 6 to 12 carbon atoms or anaralkyl group having 7 to 12 carbon atoms)

(in which R²⁸ is an alkyl group having 1 to 12 carbon atoms, acycloalkyl group having 3 to 6 carbon atoms, or an aryl group having 6to 12 carbon atoms; R²⁹ is a hydrogen atom, an alkyl group having 1 to12 carbon atoms, a cycloalkyl group having 3 to 6 carbon atoms, or anaryl group having 6 to 12 carbon atoms; and p is 1 or 2).

The non-aqueous electrolytic solution according to the present inventioncontains both a specific amount of a vinylene carbonate compound and aspecific amount of an alkyne compound. The non-aqueous electrolyticsolution can be advantageously used in a lithium secondary battery ofhigh capacity comprising a positive electrode and negative electrodecomposition layers of high density. The lithium secondary batterycomprising the non-aqueous electrolytic solution according to thepresent invention is improved in cycle characteristics without causingphenomenon of dry up. The function and effect have not yet clarified,but are considered to be obtained by a strong film formed on a negativeelectrode using both the vinylene carbonate compound and the alkynecompound. The improvement on the cycle characteristics is obtained usingthe non-aqueous electrolytic solution according to the presentinvention. The improvement is also effective in a conventional lithiumsecondary battery comprising positive electrode and negative electrodelayers of relatively low density.

Effect of the Invention

The cycle characteristics of the lithium secondary battery are improvedby using the non-aqueous electrolytic solution according to the presentinvention. The non-aqueous electrolytic solution according to thepresent invention is particularly effective in improving cyclecharacteristics of a lithium secondary battery (of high charge capacity)comprising positive electrode or negative electrode composition layer ofhigh density.

BEST MODE FOR CARRYING OUT THE INVENTION

In the vinylene carbonate compound according to the present inventionrepresented by the formula (I), each of R¹ and R² independently is ahydrogen atom or an alkyl group having 1 to 4 carbon atoms, such asmethyl, ethyl, propyl and butyl. R¹ and R² can be identical, forexample, both can be methyl or both can be ethyl. R¹ and R² can bedifferent from each other, for example, they can be a combination ofmethyl and ethyl.

Examples of the vinylene carbonate compound represented by the formula(I) include vinylene carbonate, 4-methyl-1,3-dioxolen-2-one,4-ethyl-1,3-dioxolen-2-one, 4-propyl-1,3-dioxolen-2-one,4-butyl-1,3-dioxolen-2-one, 4-tert-butyl-1,3-dioxolen-2-one,4,5-dimethyl-1,3-dioxolen-2-one, 4,5-diethyl-1,3-dioxolen-2-one,4,5-dipropyl-1,3-dioxolen-2-one, 4,5-dibutyl-1,3-dioxolen-2-one,4,5-ditert-butyl-1,3-dioxolen-2-one,4-ethyl-5-methyl-1,3-dioxolen-2-one, 4-methyl-5-butyl-1,3-dioxolen-2-oneand 4-methyl-5-tert-butyl-1,3-dioxolen-2-one. Vinylene carbonate isparticularly preferred.

An excess amount of the vinylene carbonate compound represented by theformula (I) contained in the non-aqueous electrolytic solution mightlower battery performance. On the other hand, shortage of the vinylenecarbonate might cause insufficient battery performance. The non-aqueouselectrolytic solution contains the vinylene carbonate compoundpreferably in an amount of 0.01 wt. % or more, more preferably in anamount of 0.05 wt. % or more, and most preferably in an amount of 0.1wt. % or more. Further, the non-aqueous electrolytic solution containsthe vinylene carbonate compound preferably in an amount of 10 wt. % orless, more preferably in an amount of 5 wt. % or less, and mostpreferably in an amount of 3 wt. % or less. Accordingly, the non-aqueouselectrolytic solution contains the vinylene carbonate compoundpreferably in an amount of 0.01 to 10 wt. %, more preferably in anamount of 0.05 to 5 wt. %, and most preferably in an amount of 0.1 to 3wt. %.

An alkyne compound is used in combination with the vinylene carbonatecompound in the present invention. The alkyne compound is describedbelow.

Examples of the alkyne compound represented by the formula (II) areshown below.

(1) Y¹ is —COOR²⁰

2-Propynyl methyl carbonate (each of R³, R⁴ and R⁵ is hydrogen, R²⁰ ismethyl, and x is 1)

1-Methyl-2-propynyl methyl carbonate (R³ is hydrogen, R⁴ is methyl, R⁵is hydrogen, R²⁰ is methyl, and x is 1)

2-Propynyl ethyl carbonate (each of R³, R⁴ and R⁵ is hydrogen, R²⁰ isethyl, and x is 1)

2-Propynyl propyl carbonate (each of R³, R⁴ and R⁵ is hydrogen, R²⁰ ispropyl, and x is 1)

2-Propynyl butyl carbonate (each of R³, R⁴ and R⁵ is hydrogen, R²⁰ isbutyl, and x is 1)

2-Propynyl phenyl carbonate (each of R³, R⁴ and R⁵ is hydrogen, R²⁰ isphenyl, and x is 1)

2-Propynyl cyclohexyl carbonate (each of R³, R⁴ and R⁵ is hydrogen, R²⁰is cyclohexyl, and x is 1)

2-Butynyl methyl carbonate (R³ is methyl, each of R⁴ and R⁵ is hydrogen,R²⁰ is methyl, and x is 1)

3-Butynyl methyl carbonate (each of R³, R⁴ and R⁵ is hydrogen, R²⁰ ismethyl, and x is 2)

2-Pentynyl methyl carbonate (R³ is ethyl, each of R⁴ and R⁵ is hydrogen,R²⁰ is methyl, and x is 1)

1-Methyl-2-butynyl methyl carbonate (each of R³ and R⁴ is methyl, R⁵ ishydrogen, R²⁰ is methyl, and x is 1)

1,1-Dimethyl-2-propynyl methyl carbonate (R³ is hydrogen, each of R⁴ andR⁵ is methyl, R²⁰ is methyl, and x is 1)

1,1-Diethyl-2-propynyl methyl carbonate (R³ is hydrogen, each of R⁴ andR⁵ is ethyl, R²⁰ is methyl, and x is 1)

1-Ethyl-1-methyl-2-propynyl methyl carbonate (R³ is hydrogen, R⁴ isethyl, R⁵ is methyl, R²⁰ is methyl, and x is 1)

1-Isobutyl-1-methyl-2-propynyl methyl carbonate (R³ is hydrogen, R⁴ isisobutyl, R⁵ is methyl, R²⁰ is methyl, and x is 1)

1,1-Dimethyl-2-butynyl methyl carbonate (each of R³, R⁴ and R⁵ ismethyl, R²⁰ is methyl, and x is 1)

1-Ethynylcyclohexyl methyl carbonate (R³ is hydrogen, combination of R⁴and R⁵ is pentamethylene, R²⁰ is methyl, and x is 1)

1-Methyl-1-phenyl-2-propynyl methyl carbonate (R³ is hydrogen, R⁴ isphenyl, R⁵ is methyl, R²⁰ is methyl, and x is 1)

1,1-Diphenyl-2-propynyl methyl carbonate (R³ is hydrogen, each of R⁴ andR⁵ is phenyl, R²⁰ is methyl, and x is 1)

1,1-Dimethyl-2-propynyl ethyl carbonate (R³ is hydrogen, each of R⁴ andR⁵ is methyl, R²⁰ is ethyl, and x is 1)

(2) Y¹ is —COR²⁰

2-Propynyl formate (each of R³, R⁴, R⁵ and R²⁰ is hydrogen, and x is 1)

1-Methyl-2-propynyl formate (R³ is hydrogen, R⁴ is methyl, R⁵ ishydrogen, R²⁰ is hydrogen, and x is 1)

2-Propynyl acetate (each of R³, R⁴ and R⁵ is hydrogen, R²⁰ is methyl,and x is 1)

1-Methyl-2-propynyl acetate (R³ is hydrogen, R⁴ is methyl, R⁵ ishydrogen, R²⁰ is methyl, and x is 1)

2-Propynyl propionate (each of R³, R⁴ and R⁵ is hydrogen, R²⁰ is ethyl,and x is 1)

2-Propynyl butyrate (each of R³, R⁴ and R⁵ is hydrogen, R²⁰ is propyl,and x is 1)

2-Propynyl benzoate (each of R³, R⁴ and R⁵ is hydrogen, R²⁰ is phenyl,and x is 1)

2-Propynyl cyclohexanecarboxylate (each of R³, R⁴ and R⁵ is hydrogen,R²⁰ is cyclohexyl, and x is 1)

2-Butynyl formate (R³ is methyl, each of R⁴, R⁵ and R²⁰ is hydrogen, andx is 1)

3-Butynyl formate (each of R³, R⁴, R⁵ and R²⁰ is hydrogen, and x is 2)

2-Pentynyl formate (R³ is ethyl, each of R⁴, R⁵ and R²⁰ is hydrogen, andx is 1)

1-Methyl-2-butynyl formate (each of R³ and R⁴ is methyl, each of R⁵ andR²⁰ is hydrogen, and x is 1)

1,1-Dimethyl-2-propynyl formate (R³ is hydrogen, each of R⁴ and R⁵ ismethyl, R²⁰ is hydrogen, and x is 1)

1,1-Diethyl-2-propynyl formate (R³ is hydrogen, each of R⁴ and R⁵ isethyl, R²⁰ is hydrogen, and x is 1)

1-Ethyl-1-methyl-2-propynyl formate (R³ is hydrogen, R⁴ is ethyl, R⁵ ismethyl, R²⁰ is hydrogen, and x is 1)

1-Isobutyl-1-methyl-2-propynyl formate (R³ is hydrogen, R⁴ is isobutyl,R⁵ is methyl, R²⁰ is hydrogen, and x is 1)

1,1-Dimethyl-2-butynyl formate (each of R³, R⁴ and R⁵ is methyl, R²⁰ ishydrogen, and x is 1)

1-Ethynylcyclohexyl formate (R³ is hydrogen, combination of R⁴ and R⁵ ispentamethylene, R²⁰ is hydrogen, and x is 1)

1-Methyl-1-phenyl-2-propynyl formate (R³ is hydrogen, R⁴ is phenyl, R⁵is methyl, R²⁰ is hydrogen, and x is 1)

1,1-Diphenyl-2-propynyl formate (R³ is hydrogen, each of R⁴ and R⁵ isphenyl, R²⁰ is hydrogen, and x is 1)

2-Butynyl acetate (R³ is methyl, each of R⁴ and R⁵ is hydrogen, R²⁰ ismethyl, and x is 1)

3-Butynyl acetate (each of R³, R⁴ and R⁵ is hydrogen, R²⁰ is methyl, andx is 2)

2-Pentynyl acetate (R³ is ethyl, each of R⁴ and R⁵ is hydrogen, R²⁰ ismethyl, and x is 1)

1-Methyl-2-butynyl acetate (each of R³ and R⁴ is methyl, R⁵ is hydrogen,R²⁰ is methyl, and x is 1)

1,1-Dimethyl-2-propynyl acetate (R³ is hydrogen, each of R⁴ and R⁵ ismethyl, R²⁰ is methyl, and x is 1)

1,1-Diethyl-2-propynyl acetate (R³ is hydrogen, each of R⁴ and R⁵ isethyl, R²⁰ is methyl, and x is 1)

1-Ethyl-1-methyl-2-propynyl acetate (R³ is hydrogen, R⁴ is ethyl, R⁵ ismethyl, R²⁰ is methyl, and x is 1)

1-Isobutyl-1-methyl-2-propynyl acetate (R³ is hydrogen, R⁴ is isobutyl,R⁵ is methyl, R²⁰ is methyl, and x is 1)

1,1-Dimethyl-2-butynyl acetate (each of R³, R⁴ and R⁵ is methyl, R²⁰ ismethyl, and x is 1)

1-Ethynylcyclohexyl acetate (R³ is hydrogen, combination of R⁴ and R⁵ ispentamethylene, R²⁰ is methyl, and x is 1)

1-Methyl-1-phenyl-2-propynyl acetate (R³ is hydrogen, R⁴ is phenyl, R⁵is methyl, R²⁰ is methyl, and x is 1)

1,1-Diphenyl-2-propynyl acetate (R³ is hydrogen, each of R⁴ and R⁵ isphenyl, R²⁰ is methyl, and x is 1)

1,1-Dimethyl-2-propynyl propionate (R³ is hydrogen, each of R⁴ and R⁵ ismethyl, R²⁰ is ethyl, and x is 1)

(3) Y¹ is —SO₂R²⁰

2-Propynyl methanesulfonate (each of R³, R⁴ and R⁵ is hydrogen, R²⁰ ismethyl, and x is 1)

1-Methyl-2-propynyl methanesulfonate (R³ is hydrogen, R⁴ is methyl, R⁵is hydrogen, R²⁰ is methyl, and x is 1)

2-Propynyl ethanesulfonate (each of R³, R⁴ and R⁵ is hydrogen, R²⁰ isethyl, and x is 1)

2-Propynyl propanesulfonate (each of R³, R⁴ and R⁵ is hydrogen, R²⁰ ispropyl, and x is 1)

2-Propynyl p-toluenesulfonate, (each of R³, R⁴ and R⁵ is hydrogen, R²⁰is p-tolyl, and x is 1)

2-Propynyl cyclohexanesulfonate (each of R³, R⁴ and R⁵ is hydrogen, R²⁰is cyclohexyl, and x is 1)

2-Butynyl methanesulfonate (R³ is methyl, each of R⁴ and R⁵ is hydrogen,R²⁰ is methyl, and x is 1)

3-Butynyl methanesulfonate (each of R³, R⁴ and R⁵ is hydrogen, R²⁰ ismethyl, and x is 2)

2-Pentynyl methanesulfonate (R³ is ethyl, each of R⁴ and R⁵ is hydrogen,R²⁰ is methyl, and x is 1)

1-Methyl-2-butynyl methanesulfonate (each of R³ and R⁴ is methyl, R⁵ ishydrogen, R²⁰ is methyl, and x is 1)

1,1-Dimethyl-2-propynyl methanesulfonate (R³ is hydrogen, each of R⁴ andR⁵ is methyl, R²⁰ is methyl, and x is 1)

1,1-Diethyl-2-propynyl methanesulfonate (R³ is hydrogen, each of R⁴ andR⁵ is ethyl, R²⁰ is methyl, and x is 1)

1-Ethyl-1-methyl-2-propynyl methanesulfonate (R³ is hydrogen, R⁴ isethyl, R⁵ is methyl, R²⁰ is methyl, and x is 1)

1-Isobutyl-1-methyl-2-propynyl methanesulfonate (R³ is hydrogen, R⁴ isisobutyl, R⁵ is methyl, R²⁰ is methyl, and x is 1)

1,1-Dimethyl-2-butynyl methanesulfonate (each of R³, R⁴ and R⁵ ismethyl, R²⁰ is methyl, and x is 1)

1-Ethynylcyclohexyl methanesulfonate (R³ is hydrogen, combination of R⁴and R⁵ is pentamethylene, R²⁰ is methyl, and x is 1)

1-Methyl-1-phenyl-2-propynyl methanesulfonate (R³ is hydrogen, R⁴ isphenyl, R⁵ is methyl, R²⁰ is methyl, and x is 1)

1,1-Diphenyl-2-propynyl methanesulfonate (R³ is hydrogen, each of R⁴ andR⁵ is phenyl, R²⁰ is methyl, and x is 1)

1,1-Dimethyl-2-propynyl ethanesulfonate (R³ is hydrogen, each of R⁴ andR⁵ is methyl, R²⁰ is ethyl, and x is 1)

Examples of the alkyne compound represented by the formula (III) areshown below.

(1) Y² is —COOR²¹ and Y³ is —COOR²²

2-Butynylene bis(methyl carbonate) (each of R⁶, R⁷, R⁸ and R⁹ ishydrogen, each of R²¹ and R²² is methyl, and x is 1)

2-Butynylene bis(ethyl carbonate) (each of R⁶, R⁷, R⁸ and R⁹ ishydrogen, each of R²¹ and R²² is ethyl, and x is 1)

1,4-Dimethyl-2-butynylene bis(methyl carbonate) (each of R⁶ and R⁸ ismethyl, each of R⁷ and R⁹ is hydrogen, each of R²¹ and R²² is methyl,and x is 1)

1,4-Dimethyl-2-butynylene bis(ethyl carbonate) (each of R⁶ and R⁸ ismethyl, each of R⁷ and R⁹ is hydrogen, each of R²¹ and R²² is ethyl, andx is 1) 1,1,4,4-Tetramethyl-2-butynylene bis(methyl carbonate) (each ofR⁶, R⁷, R⁸ and R⁹ is methyl, each of R²¹ and R²² is methyl, and x is 1)

1,1,4,4-Tetramethyl-2-butynylene bis(ethyl carbonate) (each of R⁶, R⁷,R⁸ and R⁹ is methyl, each of R²¹ and R²² is ethyl, and x is 1)

(2) Y² is —COR²¹ and Y³ is —COR²²

2-Butynylene diformate (each of R⁶, R⁷, R⁸, R⁹, R²¹ and R²² is hydrogen,and x is 1)

2-Butynylene diacetate (each of R⁶, R⁷, R⁸ and R⁹ is hydrogen, each ofR²¹ and R²² is methyl, and x is 1)

2-Butynylene dipropionate (each of R⁶, R⁷, R⁸ and R⁹ is hydrogen, eachof R²¹ and R²² is ethyl, and x is 1)

1,4-Dimethyl-2-butynylene diformate (each of R⁶ and R⁸ is methyl, eachof R⁷, R⁹, R²¹ and R²² is hydrogen, and x is 1)

1,4-Dimethyl-2-butynylene diacetate (each of R⁶ and R⁸ is methyl, eachof R⁷ and R⁹ is hydrogen, each of R²¹ and R²² is methyl, and x is 1)

1,4-Dimethyl-2-butynylene dipropionate (each of R⁶ and R⁸ is methyl,each of R⁷ and R⁹ is hydrogen, each of R²¹ and R²² is ethyl, and x is 1)1,1,4,4-Tetramethyl-2-butynylene diformate (each of R⁶, R⁷, R⁸ and R⁹ ismethyl, each of R²¹ and R²² is hydrogen, and x is 1)1,1,4,4-Tetramethyl-2-butynylene diacetate (each of R⁶, R⁷, R⁸ and R⁹ ismethyl, each of R²¹ and R²² is methyl, and x is 1)

1,1,4,4-Tetramethyl-2-butynylene dipropionate (each of R⁶, R⁷, R⁸ and R⁹is methyl, each of R²¹ and R²² is ethyl, and x is 1)

(3) Y² is —SO₂R²¹ and Y³ is —SO₂R²²

2-Butynylene bis(methanesulfonate) (each of R⁶, R⁷, R⁸ and R⁹ ishydrogen, each of R²¹ and R²² is methyl, and x is 1)

2-Butynylene bis(ethanesulfonate) (each of R⁶, R⁷, R⁸ and R⁹ ishydrogen, each of R²¹ and R²² is ethyl, and x is

1,4-Dimethyl-2-butynylene bis(methanesulfonate) (each of R⁶ and R⁸ ismethyl, each of R⁷ and R⁹ is hydrogen, each of R²¹ and R²² is methyl,and x is 1)

1,4-Dimethyl-2-butynylene bis(ethanesulfonate) (each of R⁶ and R⁸ ismethyl, each of R⁷ and R⁹ is hydrogen, each of R²¹ and R²² is ethyl, andx is 1) 1,1,4,4-Tetramethyl-2-butynylene bis(methanesulfonate) (each ofR⁶, R⁷, R⁸ and R⁹ is methyl, each of R²¹ and R²² is methyl, and x is 1)

1,1,4,4-Tetramethyl-2-butynylene bis(ethanesulfonate) (each of R⁶, R⁷,R⁸ and R⁹ is methyl, each of R²¹ and R²² is ethyl, and x is 1)

Examples of the alkyne compound represented by the formula (IV) areshown below.

(1) Y⁴ is —COOR²³ and Y⁵ is —COOR²⁴

2,4-Hexadiynylene bis(methyl carbonate) (each of R¹⁰, R¹¹, R¹² and R¹³is hydrogen, each of R²³ and R²⁴ is methyl, and x is 1)

2,4-Hexadiynylene bis(ethyl carbonate) (each of R¹⁰, R¹² and R¹³ ishydrogen, each of R²³ and R²⁴ is ethyl, and x is 1)

1,1,6,6-Tetramethyl-2,4-hexadiynylene bis(methyl carbonate) (each ofR¹⁰, R¹¹, R¹² and R¹³ is methyl, each of R²³ and R²⁴ is methyl, and xis 1) 1,1,6,6-Tetramethyl-2,4-hexadiynylene bis(ethyl carbonate) (eachof R¹⁰, R¹¹, R¹² and R¹³ is methyl, each of R²³ and R²⁴ is ethyl, and xis 1) 30

(2) Y⁴ is —COR²³ and Y⁵ is —COR²⁴

2,4-Hexadiynylene diformate (each of R¹⁰, R¹¹, R¹², R¹³, R²³ and R²⁴ ishydrogen, and x is 1)

2,4-Hexadiynylene diacetate (each of R¹⁰, R¹¹, R¹² and R¹³ is hydrogen,each of R²³ and R²⁴ is methyl, and x is 1)

2,4-Hexadiynylene dipropionate (each of R¹⁰, R¹¹, R¹² and R¹³ ishydrogen, each of R²³ and R²⁴ is ethyl, and x is 1)

1,1,6,6-Tetramethyl-2,4-hexadiynylene diformate (each of R¹⁰, R¹¹, R¹²and R¹³ is methyl, each of R²³ and R²⁴ is hydrogen, and x is 1)

1,1,6,6-Tetramethyl-2,4-hexadiynylene diacetate (each of R¹⁰, R¹¹, R¹²and R¹³ is methyl, each of R²³ and R²⁴ is methyl, and x is 1)

1,1,6,6-Tetramethyl-2,4-hexadiynylene dipropionate (each of R¹⁰, R¹¹,R¹² and R¹³ is methyl, each of R²³ and R²⁴ is ethyl, and x is 1)

(3) Y⁴ is —SO₂R²³ and Y⁵ is —SO₂R²⁴

2,4-Hexadiynylene bis(methanesulfonate) (each of R¹⁰, R¹¹, R¹² and R¹³is hydrogen, each of R²³ and R²⁴ is methyl, and x is 1)

2,4-Hexadiynylene bis(ethanesulfonate) (each of R¹⁰, R¹¹, R¹² and R¹³ ishydrogen, each of R²³ and R²⁴ is ethyl, and x is 1)

1,1,6,6-Tetramethyl-2,4-hexadiynylene bis(methanesulfonate) (each ofR¹⁰, R¹¹, R¹² and R¹³ is methyl, each of R²³ and R²⁴ is methyl, and x is1)

1,1,6,6-Tetramethyl-2,4-hexadiynylene bis(ethanesulfonate) (each of R¹⁰,R¹¹, R¹² and R¹³ is methyl, each of R²³ and R²⁴ is ethyl, and x is 1)

Examples of the alkyne compound represented by the formula (V) are shownbelow.

Di (2-propynyl) carbonate (each of R¹⁴, R¹⁵, R¹⁶, R¹⁷, R¹⁸ and R¹⁹ ishydrogen, and x is 1)

Bis(1-methyl-2-propynyl) carbonate (each of R¹⁴, R¹⁶, R¹⁸ and R¹⁹ ishydrogen, each of R¹⁵ and R¹⁷ is methyl, and x is 1)

Di(2-butynyl) carbonate (each of R¹⁴ and R¹⁹ is methyl, each of R¹⁵,R¹⁶, R¹⁷ and R¹⁸ is hydrogen, and x is 1)

Di(3-butynyl) carbonate (each of R¹⁴, R¹⁵, R¹⁶, R¹⁷, R¹⁸ and R¹⁹ ishydrogen, and x is 2)

Di(2-pentynyl) carbonate (each of R¹⁴ and R¹⁹ is ethyl, each of R¹⁵,R¹⁶, R¹⁷ and R¹⁸ is hydrogen, and x is 1)

Bis(1-methyl-2-butynyl) carbonate (each of R¹⁴, R¹⁵, R¹⁶ and R¹⁹ ismethyl, each of R¹⁷ and R¹⁸ is hydrogen, and x is 1)

2-Propynyl 2-butynyl carbonate (each of R¹⁴, R¹⁵, R¹⁶, R¹⁷ and R¹⁸ ishydrogen, R¹⁹ is methyl, and x is 1)

Bis(1,1-dimethyl-2-propynyl) carbonate (each of R¹⁴ and R¹⁹ is hydrogen,each of R¹⁵, R¹⁶, R¹⁷ and R¹⁸ is methyl, and x is 1)Bis(1,1-diethyl-2-propynyl) carbonate (each of R¹⁴ and R¹⁹ is hydrogen,each of R¹⁵, R¹⁶, R¹⁷ and R¹⁸ is ethyl, and x is 1)

Bis(1-ethyl-1-methyl-2-propynyl) carbonate (each of R¹⁴ and R¹⁹ ishydrogen, each of R¹⁵ and R¹⁷ is ethyl, each of R¹⁶ and R¹⁸ is methyl,and x is 1)

Bis(1-isobutyl-1-methyl-2-propynyl) carbonate (each of R¹⁴ and R¹⁹ ishydrogen, each of R¹⁵ and R¹⁷ is isobutyl, each of R¹⁶ and R¹⁸ ismethyl, and x is 1)

Bis(1,1-dimethyl-2-butynyl) carbonate (each of R¹⁴, R¹⁵, R¹⁶, R¹⁷, R¹⁸and R¹⁹ is methyl, and x is 1)

Bis(1-ethynylcyclohexyl) carbonate (each of R¹⁴ and R¹⁹ is hydrogen,combination of R¹⁵ and R¹⁶ is pentamethylene, combination of R¹⁷ and R¹⁸is pentamethylene, and x is 1).

Examples of the alkyne compound represented by the formula (VI) areshown below.

(1) W is sulfinyl

Di(2-propynyl)sulfite (each of R²⁵, R²⁶ and R²⁷ is hydrogen, Y⁶ is2-propynyl, and x is 1)

Bis(1-methyl-2-propynyl)sulfite (R²⁵ is hydrogen, R²⁶ is methyl, R²⁷ ishydrogen, Y⁶ is 1-methyl-2-propynyl, and x is 1)

Di(2-butynyl)sulfite (R²⁵ is methyl, each of R²⁶ and R²⁷ is hydrogen, Y⁶is 2-butynyl, and x is 1)

Di(3-butynyl)sulfite (each of R²⁵, R²⁶ and R²⁷ is hydrogen, Y⁶ is3-butynyl, and x is 2)

Di(2-pentynyl)sulfite (R²⁵ is ethyl, each of R²⁶ and R²⁷ is hydrogen, Y⁶is 2-pentynyl, and x is 1)

Bis(1-methyl-2-butynyl)sulfite (each of R²⁵ and R²⁶ is methyl, R²⁷ ishydrogen, Y⁶ is 1-methyl-2-butynyl, and x is 1)

Bis(1,1-dimethyl-2-propynyl)sulfite (R²⁵ is hydrogen, each of R²⁶ andR²⁷ is methyl, Y⁶ is 1,1-dimethyl-2-propynyl, and x is 1)

Bis(1,1-diethyl-2-propynyl)sulfite (R²⁵ is hydrogen, each of R²⁶ and R²⁷is ethyl, Y⁶ is 1,1-diethyl-2-propynyl, and x is 1)

Bis(1-ethyl-1-methyl-2-propynyl)sulfite (R²⁵ is hydrogen, R²⁶ is ethyl,R²⁷ is methyl, Y⁶ is 1-ethyl-1-methyl-2-propynyl, and x is 1)

Bis(1-isobutyl-1-methyl-2-propynyl)sulfite (R²⁵ is hydrogen, R²⁶ isisobutyl, R²⁷ is methyl, Y⁶ is 1-isobutyl-1-methyl-2-propynyl, and x is1)

Bis(1,1-dimethyl-2-butynyl)sulfite (each of R²⁵, R²⁶ and R²⁷ is methyl,Y⁶ is 1,1-dimethyl-2-butynyl, and x is 1)

Bis(1-ethynylcyclohexyl) sulfite (R²⁵ is hydrogen, combination of R²⁶and R²⁷ is pentamethylene, Y⁶ is 1-ethynylcyclohexyl, and x is 1)

Bis(1-methyl-1-phenyl-2-propynyl)sulfite (R²⁵ is hydrogen, R²⁶ isphenyl, R²⁷ is methyl, Y⁶ is 1-methyl-1-phenyl-2-propynyl, and x is 1)

Bis(1,1-diphenyl-2-propynyl)sulfite (R²⁵ is hydrogen, each of R²⁶ andR²⁷ is phenyl, Y⁶ is 1,1-diphenyl-2-propynyl, and x is 1)

Methyl 2-propynyl sulfite (each of R²⁵, R²⁶ and R²⁷ is hydrogen, Y⁶ ismethyl, and x is 1)

Methyl 1-methyl-2-propynyl sulfite (R²⁵ is hydrogen, R²⁶ is methyl, R²⁷is hydrogen, Y⁶ is methyl, and x is 1)

Ethyl 2-propynyl sulfite (each of R²⁵, R²⁶ and R²⁷ is hydrogen, Y⁶ isethyl, and x is 1)

Phenyl 2-propynyl sulfite (each of R²⁵, R²⁶ and R²⁷ is hydrogen, Y⁶ isphenyl, and x is 1)

Cyclohexyl 2-propynyl sulfite (each of R²⁵, R²⁶ and R²⁷ is hydrogen, Y⁶is cyclohexyl, and x is 1)

(2) W is sulfonyl

Di(2-propynyl)sulfate (each of R²⁵, R²⁶ and R²⁷ is hydrogen Y⁶ is2-propynyl, and x is 1)

Bis(1-methyl-2-propynyl)sulfate (R²⁵ is hydrogen, R²⁶ is methyl, R²⁷ ishydrogen, Y⁶ is 1-methyl-2-propynyl, and x is 1)

Di(2-butynyl)sulfate (R²⁵ is methyl, each of R²⁶ and R²⁷ is hydrogen, Y⁶is 2-butynyl, and x is 1)

Di(3-butynyl)sulfate (each of R²⁵, R²⁶ and R²⁷ is hydrogen, Y⁶ is3-butynyl, and x is 2)

Di(2-pentynyl)sulfate (R²⁵ is ethyl, each of R²⁶ and R²⁷ is hydrogen, Y⁶is 2-pentynyl, and x is 1)

Bis(1-methyl-2-butynyl)sulfate (each of R²⁵ and R²⁶ is methyl, R²⁷ ishydrogen, Y⁶ is 1-methyl-2-butynyl, and x is 1)

Bis(1,1-dimethyl-2-propynyl)sulfate (R²⁵ is hydrogen, each of R²⁶ andR²⁷ is methyl, Y⁶ is 1,1-dimethyl-2-propynyl, and x is 1)

Bis(1,1-diethyl-2-propynyl)sulfate (R²⁵ is hydrogen, each of R²⁶ and R²⁷is ethyl, Y⁶ is 1,1-diethyl-2-propynyl, and x is 1)

Bis(1-ethyl-1-methyl-2-propynyl)sulfate (R²⁵ is hydrogen, R²⁶ is ethyl,R²⁷ is methyl, Y⁶ is 1-ethyl-1-methyl-2-propynyl, and x is 1)

Bis(1-isobutyl-1-methyl-2-propynyl)sulfate (R²⁵ is hydrogen, R²⁶ isisobutyl, R²⁷ is methyl, Y⁶ is 1-isobutyl-1-methyl-2-propynyl, and x is1)

Bis(1,1-dimethyl-2-butynyl)sulfate (each of R²⁵, R²⁶ and R²⁷ is methyl,Y⁶ is 1,1-dimethyl-2-butynyl, and x is 1)

Bis(1-ethynylcyclohexyl) sulfate (R²⁵ is hydrogen, combination of R²⁶and R²⁷ is pentamethylene, Y⁶ is 1-ethynylcyclohexyl, and x is 1)

Bis(1-methyl-1-phenyl-2-propynyl)sulfate (R²⁵ is hydrogen, R²⁶ isphenyl, R²⁷ is methyl, Y⁶ is 1-methyl-1-phenyl-2-propynyl, and x is 1)

Bis(1,1-diphenyl-2-propynyl)sulfate (R²⁵ is hydrogen, each of R²⁶ andR²⁷ is phenyl, Y⁶ is 1,1-diphenyl-2-propynyl, and x is 1)

Methyl 2-propynyl sulfate (each of R²⁵, R²⁶ and R²⁷ is hydrogen, Y⁶ ismethyl, and x is 1)

Methyl 1-methyl-2-propynyl sulfate (R²⁵ is hydrogen, R²⁶ is methyl, R²⁷is hydrogen, Y⁶ is methyl, and x is 1)

Ethyl 2-propynyl sulfate (each of R²⁵, R²⁶ and R²⁷ is hydrogen, Y⁶ isethyl, and x is 1)

Phenyl 2-propynyl sulfate (each of R²⁵, R²⁶ and R²⁷ is hydrogen, Y⁶ isphenyl, and x is 1)

Cyclohexyl 2-propynyl sulfate (each of R²⁵, R²⁶ and R²⁷ is hydrogen, Y⁶is cyclohexyl, and x is 1)

(3) W is oxalyl

Di (2-propynyl)oxalate (each of R²⁵, R²⁶ and R²⁷ is hydrogen, Y⁶ is2-propynyl, and x is 1)

Bis(1-methyl-2-propynyl)oxalate (R²⁵ is hydrogen, R²⁶ is methyl, R²⁷ ishydrogen, Y⁶ is 1-methyl-2-propynyl, and x is 1)

Di(2-butynyl)oxalate (R²⁵ is methyl, each of R²⁶ and R²⁷ is hydrogen, Y⁶is 2-butynyl, and x is 1)

Di(3-butynyl)oxalate (each of R²⁵, R²⁶ and R²⁷ is hydrogen, Y⁶ is3-butynyl, and x is 2)

Di(2-pentynyl)oxalate (R²⁵ is ethyl, each of R²⁶ and R²⁷ is hydrogen, Y⁶is 2-pentynyl, and x is 1)

Bis(1-methyl-2-butynyl)oxalate (each of R²⁵ and R²⁶ is methyl, R²⁷ ishydrogen, Y⁶ is 1-methyl-2-butynyl, and x is 1)

Bis(1,1-dimethyl-2-propynyl)oxalate (R²⁵ is hydrogen, each of R²⁶ andR²⁷ is methyl, Y⁶ is 1,1-dimethyl-2-propynyl, and x is 1)

Bis(1,1-diethyl-2-propynyl)oxalate (R²⁵ is hydrogen, each of R²⁶ and R²⁷is ethyl, Y⁶ is 1,1-diethyl-2-propynyl, and x is 1)

Bis(1-ethyl-1-methyl-2-propynyl)oxalate (R²⁵ is hydrogen, R²⁶ is ethyl,R²⁷ is methyl, Y⁶ is 1-ethyl-1-methyl-2-propynyl, and x is 1)

Bis(1-isobutyl-1-methyl-2-propynyl)oxalate (R²⁵ is hydrogen, R²⁶ isisobutyl, R²⁷ is methyl, Y⁶ is 1-isobutyl-1-methyl-2-propynyl, and x is1)

Bis(1,1-dimethyl-2-butynyl)oxalate (each of R²⁵, R²⁶ and R²⁷ is methyl,Y⁶ is 1,1-dimethyl-2-butynyl, and x is 1)

Bis(1-ethynylcyclohexyl)oxalate (R²⁵ is hydrogen, combination of R²⁶ andR²⁷ is pentamethylene, Y⁶ is 1-ethynylcyclohexyl, and x is 1)

Bis(1-methyl-1-phenyl-2-propynyl)oxalate (R²⁵ is hydrogen, R²⁶ isphenyl, R²⁷ is methyl, Y⁶ is 1-methyl-1-phenyl-2-propynyl, and x is 1)

Bis(1,1-diphenyl-2-propynyl)oxalate (R²⁵ is hydrogen, each of R²⁶ andR²⁷ is phenyl, Y⁶ is 1,1-diphenyl-2-propynyl, and x is 1)

Methyl 2-propynyl oxalate (each of R²⁵, R²⁶ and R²⁷ is hydrogen, Y⁶ ismethyl, and x is 1)

Methyl 1-methyl-2-propynyl oxalate (R²⁵ is hydrogen, R²⁶ is methyl, R²⁷is hydrogen, Y⁶ is methyl, and x is 1)

Ethyl 2-propynyl oxalate (each of R²⁵, R²⁶ and R²⁷ is hydrogen, Y⁶ isethyl, and x is 1)

Phenyl 2-propynyl oxalate (each of R²⁵, R²⁶ and R²⁷ is hydrogen, Y⁶ isphenyl, and x is 1)

Cyclohexyl 2-propynyl oxalate (each of R²⁵, R²⁶ and R²⁷ is hydrogen, Y⁶is cyclohexyl, and x is 1)

Examples of the alkyne compound represented by the formula (VII) areshown below.

2-Pentyne (R²⁸ is methyl, R²⁹ is ethyl, and p is 1)

1-Hexyne (R²⁸ is butyl, R²⁹ is hydrogen, and p is 1)

2-Hexyne (R²⁸ is propyl, R²⁹ is methyl, and p is 1)

3-Hexyne (each of R²⁸ and R²⁹ is ethyl, and p is 1)

1-Heptyne (R²⁸ is pentyl, R²⁹ is hydrogen, and p is 1)

1-Octyne (R²⁸ is hexyl, R²⁹ is hydrogen, and p is 1)

2-Octyne (R²⁸ is methyl, R²⁹ is pentyl, and p is 1)

4-Octyne (each of R²⁸ and R²⁹ is propyl, and p is 1)

1-Decyne (R²⁸ is octyl, R²⁹ is hydrogen, and p is 1)

1-Dodecyne (R²⁸ is decyl, R²⁹ is hydrogen, and p is 1)

Phenylacetylene (R²⁸ is phenyl, R²⁹ is hydrogen, and p is 1)

1-Phenyl-1-propyne (R²⁸ is phenyl, R²⁹ is methyl, and p is 1)

1-Phenyl-1-butyne (R²⁸ is phenyl, R²⁹ is ethyl, and p is 1)

1-Phenyl-1-pentyne (R²⁸ is phenyl, R²⁹ is propyl, and p is 1)

1-Phenyl-1-hexyne (R²⁸ is phenyl, R²⁹ is butyl, and p is 1)

Diphenylacetylene (each of R²⁸ and R²⁹ is phenyl, and p is 1)

4-Ethynyltoluene (R²⁸ is p-tolyl, R²⁹ is hydrogen, and p is 1)

4-Tert-butylphenylacetylene (R²⁸ is 4-tertbutylphenyl, R²⁹ is hydrogen,and p is 1)

1-Ethynyl-4-fluorobenzene (R²⁸ is p-fluorophenyl, R²⁹ is hydrogen, and pis 1)

1,4-Diethynylbenzene (R²⁸ is p-ethynylphenyl, R²⁹ is hydrogen, and p is1)

Dicyclohexylacetylene (each of R²⁸ and R²⁹ is cyclohexyl, and p is 1)

1,4-Diphenylbutadiyne (each of R²⁸ and R²⁹ is phenyl, and p is 2)

An excess amount of the alkyne compound contained in the non-aqueouselectrolytic solution might change conductivity of the electrolyticsolution to lower battery performance. The electrolytic solutioncontains the alkyne compound preferably in an amount of 10 wt. % orless, more preferably in an amount of 5 wt. % or less, and mostpreferably in an amount of 3 wt. % or less. On the other hand, it isdifficult to form a film from an extremely small amount of the alkynecompound. Therefore, shortage of the alkyne compound might causeinsufficient battery performance. The electrolytic solution contains thealkyne compound preferably in an amount of 0.01 wt. % or more, morepreferably in an amount of 0.05 wt. % or more, and most preferably in anamount of 0.1 wt. % or more. Accordingly, the non-aqueous electrolyticsolution contains the alkyne compound preferably in an amount of 0.01 to10 wt. %, more preferably in an amount of 0.05 to 5 wt. %, and mostpreferably in an amount of 0.1 to 3 wt. %.

Examples of the non-aqueous solvent used in the non-aqueous electrolyticsolution according to the present invention include: cyclic carbonatessuch as ethylene carbonate (EC), propylene carbonate (PC), butylenecarbonate (BC), vinylethylene carbonate (VEC); lactones such asγ-butyrolactone (GBL), γ-valerolactone (GVL), α-angelica lactone (AGL);chain carbonates such as dimethyl carbonate (DMC), methyl ethylcarbonate (NEC), diethyl carbonate (DEC), methyl propyl carbonate (MPC),dipropyl carbonate (DPC), methyl butyl carbonate (MBC), dibutylcarbonate (DBC); ethers such as tetrahydrofuran,2-methyltetrahydrofuran, 1,4-dioxane, 1,2-dimethoxyethane,1,2-diethoxyethane, 1,2-dibutoxyethane; nitriles such as acetonitrile,adiponitrile; chain esters such as methyl propionate, methyl pivalate,butyl pivalate, octyl pivalate; amides such as dimethylformamide;phosphoric esters such as trimethyl phosphate, trioctyl phosphate; andcompounds having a structure of S═O such as 1,3-propanesultone,1,4-propanesultone, divinyl sulfone, tetramethylenebis(methanesulfonate), ethylene sulfite, propylene sulfite, ethylenesulfate, propylene sulfate.

Examples of combination of the non-aqueous solvents include variouscombinations such as a combination of a cyclic carbonate and a chaincarbonate, a combination of a cyclic carbonate and a lactone, acombination of a cyclic carbonate, a lactone and a chain ester, acombination of a cyclic carbonate, a chain carbonate and a lactone, acombination of a cyclic carbonate, a chain carbonate and an ether, and acombination of a cyclic carbonate, a chain carbonate and a chain ester.The combination of the cyclic carbonate and the chain carbonate, or thecombination of the cyclic carbonate, the lactone and the chain carbonateis preferred. The volume ratio of the cyclic carbonate to the chaincarbonate is preferably in the range of 1:9 to 10:0, and more preferablyin the range of 2:8 to 7:3.

Examples of the electrolyte salt used in the non-aqueous electrolyticsolution include: LiPF₆; LiBF₄; LiClO₄; lithium salts comprising a chainalkyl group such as LiN(SO₂CF₃)₂, LiN(SO₂C₂F₅)₂, LiC(SO₂CF₃)₃,LiPF₄(CF₃)₂, LiPF₃(C₂F₅)₃, LiPF₃(CF₃)₃, LiPF₃(iso-C₃F₇)₃,LiPF₅(isoC₃F₇); and lithium salts comprising a cyclic alkylene groupsuch as (CF₂)₂(SO₂)₂NLi, (CF₂)₃(SO₂)₂NLi. Only one electrolyte salt canbe used in the solution. Further, two or more electrolyte salts can beused in combination. The concentration of the electrolyte saltsdissolved in the non-aqueous medium is preferably of 0.3 M or more, morepreferably of 0.5 M or more, and most preferably of 0.7 M or more. Theconcentration is preferably of 3 M or less, more preferably of 2.5 M orless, and most preferably of 2 M or less.

The non-aqueous electrolytic solution according to the present inventioncan be obtained by mixing non-aqueous solvents such as ethylenecarbonate, propylene carbonate, methyl ethyl carbonate, dissolving theabove-mentioned electrolyte salt in the mixture, and dissolving avinylene carbonate compound and an alkyne compound in the solution.

The non-aqueous electrolytic solution according to the present inventioncan contain the air or carbon dioxide to inhibit generation of a gascaused by decomposition of the electrolytic solution and to improvebattery performance such as cycle and storage characteristics.

Carbon dioxide or the air can be contained (dissolved) in thenon-aqueous electrolytic solution in the present invention according toa method (1) of contacting the non-aqueous electrolytic solution to theair or a gas containing carbon dioxide to introduce the air or the gasinto the solution, and then injecting the solution into the battery, ora method of (2) injecting the non-aqueous electrolytic solution into thebattery, and then introducing the air or a gas containing carbon dioxideinto the battery before or after sealing the battery. The two methodscan be used in combination. The amount of the moisture contained in theair or the gas containing carbon dioxide is preferably small aspossible. The amount of the moisture is so reduced that the due point ofthe air or the gas is lower than 40° C., and more preferably lower than−50° C.

The non-aqueous electrolytic solution according to the present inventioncan further contain an aromatic compound to secure safety of the batteryfrom excessive charge. Examples of the aromatic compound includecyclohexylbenzene, a fluorocyclohexylbenzene compound (e.g.,1-fluoro-2-cyclohexylbenzene, 1-fluoro-3-cyclohexylbenzene,1-fluoro-4-cyclohexylbenzene), biphenyl, terphenyl (o-, m-, p-),diphenyl ether, 2-fluorophenyl phenyl ether, 4-fluorophenyl phenylether, fluorobenzene, difluorobenzene (o-, m-, p-), 2-fluorobiphenyl,4-fluorobiphenyl, 2,4-difluoroanisole, tert-butylbenzene,1,3-di-tert-butylbenzene, 1-fluoro-4-tert-butylbenzene,tert-pentylbenzene, 4-tertbutylbiphenyl, tert-pentylbiphenyl, apartially hydrogenated o-terphenyl (such as 1,2-dicyclohexylbenzene,2-phenylbicyclohexyl, 1,2-diphenylcyclohexane, ocyclohexylbiphenyl), apartially hydrogenated m-terphenyl (examples analogous to the examplesof the partially hydrogenated o-terphenyl) and a partially hydrogenatedp-terphenyl (examples analogous to the examples of the partiallyhydrogenated o-terphenyl). The non-aqueous electrolytic solutioncontains the aromatic compound preferably in an amount of 0.1 to 5 wt.%.

Two or more aromatic compounds can be used in combination. Examples ofthe combination include biphenyl and cyclohexylbenzene,cyclohexylbenzene and tertbutylbenzene, cyclohexylbenzene andtert-pentylbenzene, biphenyl and fluorobenzene, cyclohexylbenzene andfluorobenzene, 2,4-difluoroanisole and cyclohexylbenzene,cyclohexylbenzene and 1-fluoro-4-tert-butylbenzene, cyclohexylbenzeneand a fluorocyclohexylbenzene compound, a fluorocyclohexylbenzenecompound and fluorobenzene, and 2,4-difluoroanisole and afluorocyclohexylbenzene compound. The weight mixing ratio is preferablyin the range of 50:50 to 10:90, more preferably in the range of 50:50 to20:80, and most preferably in the range of 50:50 to 25:75. In thenon-aqueous electrolytic solution system containing the vinylenecarbonate compound and the alkyne compound, at least one aromaticcompound preferably is a compound substituted with a fluorine atom. Afluorocyclohexylbenzene compound is particularly preferred.

The non-aqueous electrolytic solution according to the present inventioncan be used as a part of a secondary battery, particularly a lithiumsecondary battery. There is no specific limitation with respect to partsof the secondary battery other than the non-aqueous electrolyticsolution. Conventional various parts can be used in the secondarybattery.

Examples of the active cathode material include a complex metal oxide oflithium with cobalt, manganese or nickel. Only one material can beselected and used as the active cathode material. Further, two or moreactive cathode materials can be used in combination. Examples of thecomplex metal oxide include LiCoO₂, LiMn₂O₄, LiNiO₂, LiCO_(1-x)NixO₂(0.01<x<1). Examples of the mixture include LiCoO₂ and LiMn₂O₄, LiCoO₂and LiNiO₂, LiMn₂O₄ and LiNiO₂. The active cathode material preferablyis a complex metal oxide of lithium, such as LiCoO₂, LiMn₂O₄, LiNiO₂.The material more preferably shows voltage of 4.3 V or more when thevoltage of an open-circuit is measured using lithium as standard aftercomplete the charge. The cathode material most preferably is a complexmetal oxide of lithium containing Co or Ni. A part of a complex metaloxide of lithium can be replaced with another metal. For example, a partof Co contained in LiCoO₂ can be replaced with Sn, Mg, Fe, Ti, Al, Zr,Cr, V, Ga, Zn or Cu.

An electroconductive material that does not cause a chemical change canbe used as the conductive material for the negative electrode. Examplesof the conductive material include graphites such as natural graphite(e.g., scaly graphite), artificial graphite, and carbon blacks such asacetylene black, ketjenblack, channel black, furnace black, lamp black,thermal black. Graphite and carbon black can be used in combination at acertain mixing ratio. The cathode composite contains the conductivematerial preferably in an amount of 1 to 10 wt. %, and more preferablyin an amount of 2 to 5 wt. %.

The positive electrode can be formed by mixing the active cathodematerial with the conductive material such as acetylene black, carbonblack, and a binder to prepare a positive electrode composite material,pressing the positive electrode material on a collecting material, andheating them at a temperature of 50 to 250° C. for about 2 hours underreduced pressure. Examples of the binder include polytetrafluoroethylene(PTFE), polyvinylidene fluoride (PVDF), styrene/butadiene copolymer(SBR), acrylonitrile/butadiene copolymer (NBR), andcarboxymethylcellulose (CMC). Examples of the collecting materialinclude aluminum foil and a stainless lath board.

A material capable of absorbing and releasing lithium is used as thenegative electrode. Examples of the material include metallic lithium,lithium alloy, a carbon material such as thermally decomposed carbon,coke, graphite (e.g., artificial graphite, natural graphite), acombustion product of an organic polymeric compound, or carbon fiber,tin, a tin compound, silicon, and a silicon compound.

The negative electrode (active anode material) preferably comprises acarbon material having a distance (d₀₀₂) between lattice faces (002) of0.340 nm or less. The carbon material more preferably is graphite havinga graphitic crystal structure with the distance (d₀₀₂) in the range of0.335 to 0.340 nm. Only one material can be selected and used as theactive anode material. Further, two or more active anode materials canbe used in combination. A powdery material such as the carbon materialcan be used as a negative electrode composite material by mixing thematerial with a binder. Examples of the binder includeethylene/propylene diene interpolymer (EPDM), polytetrafluoroethylene(PTFE), polyvinylidene fluoride (PVDF), styrene/butadiene copolymer(SBR), acrylonitrile/butadiene copolymer (NBR), andcarboxymethylcellulose (CMC). There is no specification with respect tothe method for forming the negative electrode. The anode can be preparedin the same manner as in the above-mentioned method for forming thepositive electrode.

There is no specific limitation with respect to the structure of thelithium secondary battery according to the present invention. Examplesof the structure include a coin-shaped battery comprising a positiveelectrode, a negative electrode and a separator in the form of one ormore layers, and a cylindrical or square-shaped battery comprising apositive electrode, a negative electrode and a separator in the form ofa roll. A known separator such as a minute porous material, a fabric,and a non-woven fabric can be used in the battery. The minute parousmaterial can be made of polyolefin such as polypropylene, orpolyethylene. The separator for the battery can be a single layer of aporous film. The separator can also comprise two or more porous films.The separator for the battery used in the present invention has gaspermeability preferably in the range of 50 to 1,000 seconds per 100 cc,more preferably in the range of 100 to 800 seconds per 100 cc, and mostpreferably in the range of 300 to 500 seconds per 100 cc. In the casethat the gas permeability is extremely high, the conductivity of lithiumion is lowered to cause insufficient function as battery separator. Inthe case that the gas permeability is extremely low, the mechanicalstrength is degraded. The void volume ratio is preferably in the rangeof 30 to 60%, more preferably in the range of 35 to 55%, and mostpreferably in the range of 40 to 50%. The void ratio is so adjusted toimprove the battery capacity. The thickness of the separator for thebattery is preferably thin to increase the energy density. On the otherhand, the mechanical strength and the performance can also be consideredabout the thickness. The thickness of the separator is preferably in therange of 5 to 50 μm, more preferably in the range of 10 to 40 μm, andmost preferably in the range of 15 to 25 μm.

The non-aqueous electrolytic solution according to the present inventionis particularly effective in a lithium secondary battery in which apositive electrode and negative electrode composition layers are formedas high density layers. The positive electrode composition layer formedon aluminum foil has a density preferably in the range of 3.2 to 4.0g/cm³, more preferably in the range of 3.3 to 3.9 g/cm³, and mostpreferably in the range of 3.4 to 3.8 g/cm³. If the density of thepositive electrode is more than 4.0 g/cm³, it is substantially difficultto prepare the battery. The negative electrode composition layer formedon copper foil has a density preferably in the range of 1.3 to 2.0g/cm³, more preferably in the range of 1.4 to 1.9 g/cm³, and mostpreferably in the range of 1.5 to 1.8 g/cm³. If the density of thenegative electrode is more than 2.0 g/cm³, it is substantially difficultto prepare the battery.

The electrode layer of the positive electrode according to the presentinvention has a thickness (per one surface of the collector) preferablyin the range of 30 to 120 μm, and more preferably in the range of 50 to100 μm. The electrode layer of the negative electrode according to thepresent invention has a thickness (per one surface of the collector)preferably in the range of 1 to 100 μm, and more preferably in the rangeof 3 to 70 μm. If the thickness is smaller than the preferred range, thequantity of an active material in the electrode material layer islowered to decrease the battery capacity. If the thickness is largerthan the preferred range, the cycle characteristics or the ratecharacteristics are unfavorably degraded.

There is no specific limitation with respect to the structure of thelithium secondary battery. Examples of the structure include acoin-shaped battery, a cylindrical battery, a square-shaped battery anda laminated battery, each of which comprises a positive electrode, anegative electrode, a porous separating membrane and an electrolyticsolution.

The lithium secondary battery according to the present invention showsexcellent cycle characteristics for a long term even if the finalrecharging voltage is higher than 4.2 V. The battery further showsexcellent cycle characteristics even if the final recharging voltage ishigher than 4.3 V. The final discharging voltage can be 2.5 V or more,and further can be 2.8 V or more. There is no specific limitation withrespect to the current. The battery is generally discharged with theconstant current of 0.1 to 3 C. The lithium secondary battery accordingto the present invention can be charged and discharged at a temperatureof higher than −40° C., and preferably at a temperature of higher than0° C. The battery can also be charged and discharged at a temperature oflower than 100° C., and preferably at a temperature of lower than 80° C.

A safety valve can be attached to a sealing plate to prevent the innerpressure from increasing in the lithium secondary battery according tothe present invention. A part of the battery such as a battery cell(can) or a gasket can be cut to prevent the pressure from increasing. Atleast one of various conventional safety attachments (for exampleovercurrent-preventing devices such as a fuse, a bimetal and a PTCelement) is preferably attached to the battery.

Two or more lithium secondary batteries according to the presentinvention can be placed in a battery package while arranging thebatteries in series or parallel. A safety circuit (which has functionsof monitoring conditions such as voltage, temperature and current ineach of the battery or in the combined batteries, and breaking thecurrent) can be attached to the battery package in addition to a safetyattachment such as a PTC element, a thermal fuse, a fuse and a currentbreaker.

EXAMPLES

The present invention is described by referring to the followingexamples.

Example 1 Preparation of Non-Aqueous Electrolytic Solution

A non-aqueous solvent of EC:PC:MEC having a volume ratio of 30:5:65 wasprepared. In the solvent, LiPF₆ was dissolved to prepare a 1 M solutionof an electrolyte salt. To the non-aqueous electrolytic solution, 0.1wt. % of 2-propynyl methyl carbonate (an alkyne compound represented bythe formula (II), based on the non-aqueous electrolytic solution) wasadded. To the solution, 3 wt. % of vinylene carbonate (based on thenon-aqueous electrolytic solution) was further added.

(Preparation of Lithium Secondary Battery and Measurement of BatteryPerformance)

With 94 wt. % of LiCoO₂ (active cathode material), 3 wt. % of acetyleneblack (conductive material) and polyvinylidene fluoride (binder) weremixed. To the mixture, 1-methyl-2-pyrrolidone (solvent) was added. Asurface of aluminum foil was coated with the resulting solution. Themixture was dried, molded under pressure, and heated to form a positiveelectrode composition layer (cathode).

With 95 wt. % of artificial graphite (active anode material) having agraphitic crystalline structure with a distance (d₀₀₂) of 0.335 nmbetween the lattice between lattice faces (002), 5 wt. % ofpolyvinylidene fluoride (binder) was mixed. To the mixture,1-methyl-2-pyrrolidone (solvent) was added. A surface of copper foil wascoated with the resulting solution. The mixture was dried, molded underpressure and heated to form a negative electrode composition layer(anode).

The positive electrode, the negative electrode and a separatorcomprising a micro porous polyethylene film (thickness: 20 μm) wereplaced in a battery vessel. The non-aqueous electrolytic solution waspoured into the battery. The air having the dew point of −60° C. wasintroduced into the battery, and the battery was sealed to prepare acylindrical battery having the size of 18650 (diameter: 18 mm, height:65 mm). A pressure-discharging opening and an inner current breaker (PTCelement) were attached to the battery. The positive electrodecomposition layer has the density of 3.5 g/cm³, and the negativeelectrode composition layer has the density of 1.6 g/cm³. The positiveelectrode composition layer has the thickness of 70 μm (per one surfaceof the collector), and the negative electrode composition layer has thethickness of 60 μm (per one surface of the collector).

The 18650 battery was charged with the constant current of 2.2 A (1C) ata high temperature (60° C.) to reach 4.2 V. The battery was furthercharged under the constant voltage for 3 hours in total to reach thefinal voltage of 4.2 V. The battery, was discharged under the constantcurrent of 2.2 A (1C) to reach the final voltage of 3.0 V. The cycle ofcharge and discharge was repeated. The initial discharging capacity(mAh) was the substantially same as the result using 1M ofLiPF₃-EC/PC/MEC (volume ratio: 30/5/65) containing no alkyne compound asthe non-aqueous electrolytic solution (Comparison Example 1 describedbelow). The battery performance was measured after 300 cycles. Theremaining rate of the discharging capacity to the initial dischargingcapacity (100%) was 79.2%. The initial discharging capacity (relativevalue) and the remaining rate of the discharging capacity after 300cycles are set forth in Table 1.

Examples 2-4

Cylindrical batteries having the size of 18650 were prepared in the samemanner as in Example 1, except that non-aqueous electrolytic solutionswere prepared using 0.5 wt. %, 1 wt. % and 5 wt. % of 2-propynyl methylcarbonate respectively as the additive. The cycle of charge anddischarge was tested in the same manner as in Example 1. The initialdischarging capacity (relative value) and the remaining rate of thedischarging capacity after 300 cycles are set forth in Table 1.

Example 5

A cylindrical battery having the size of 18650 was prepared in the samemanner as in Example 1, except that a non-aqueous electrolytic solutionwas prepared using 1 wt. % of 2-propynyl methyl carbonate and 0.1 wt. %of vinylene carbonate as the additives. The cycle of charge anddischarge was tested in the same manner as in Example 1. The initialdischarging capacity (relative value) and the remaining rate of thedischarging capacity after 300 cycles are set forth in Table 1.

Example 6

A cylindrical battery having the size of 18650 was prepared in the samemanner as in Example 1, except that a non-aqueous electrolytic solutionwas prepared using 1 wt. % of 2-propynyl methyl carbonate and 5 wt. % ofvinylene carbonate as the additives. The cycle of charge and dischargewas tested in the same manner as in Example 1. The initial dischargingcapacity (relative value) and the remaining rate of the dischargingcapacity after 300 cycles are set forth in Table 1.

Comparison Example 1

A cylindrical battery having the size of 18650 was prepared in the samemanner as in Example 1, except that a non-aqueous electrolytic solutionwas prepared using no 2-propynyl methyl carbonate and 3 wt. % ofvinylene carbonate as the additives. The cycle of charge and dischargewas tested in the same manner as in Example 1. The initial dischargingcapacity (relative value) and the remaining rate of the dischargingcapacity after 300 cycles are set forth in Table 1.

Comparison Example 2

A cylindrical battery having the size of 18650 was prepared in the samemanner as in Example 1, except that a non-aqueous electrolytic solutionwas prepared using 3 wt. % of 2-propynyl methyl carbonate and novinylene carbonate as the additives. The cycle of charge and dischargewas tested in the same manner as in Example 1. The initial dischargingcapacity (relative value) and the remaining rate of the dischargingcapacity after 300 cycles are set forth in Table 1.

TABLE 1 Lithium 2-Propynyl Initial Remaining secondary Vinylene methyldischarging rate of battery carbonate carbonate capacity capacityExample 1 3 wt. % 0.1 wt. % 1.00 79.2% Example 2 3 wt. % 0.5 wt. % 1.0082.1% Example 3 3 wt. % 1 wt. % 1.00 82.5% Example 4 3 wt. % 5 wt. %1.00 81.1% Example 5 0.1 wt. % 1 wt. % 1.00 78.3% Example 6 5 wt. % 1wt. % 1.00 80.1% Comp. Ex. 1 3 wt. % 0 wt. % 1.00 64.3% Comp. Ex. 2 0wt. % 3 wt. % 1.00 65.8%

As is evident from the results shown in Table 1, a discharging capacityis kept with a high remaining rate. The excellent cycle characteristicsare achieved by adding both of a vinylene carbonate compound and analkyne compound to a non-aqueous electrolytic solution according to thepresent invention.

Example 7

A cylindrical battery having the size of 18650 was prepared in the samemanner as in Example 1, except that a non-aqueous electrolytic solutionwas prepared using 1 wt. % of 2-propynyl methanesulfonate (a compoundrepresented by the formula (II)) as the alkyne compound. The cycle ofcharge and discharge was tested in the same manner as in Example 1. Theresults are shown below.

Initial discharging capacity (relative value):

1.00

Remaining rate of discharging capacity after 300 cycles:

82.7

Example 8

A cylindrical battery having the size of 18650 was prepared in the samemanner as in Example 1, except that a non-aqueous electrolytic solutionwas prepared using 1 wt. % of 2-butynylene bis(methyl carbonate) (acompound represented by the formula (III)) as the alkyne compound. Thecycle of charge and discharge was tested in the same manner as inExample 1. The results are shown below.

Initial discharging capacity (relative value):

100

Remaining rate of discharging capacity after 300 cycles:

81.3

Example 9

A cylindrical battery having the size of 18650 was prepared in the samemanner as in Example 1, except that a non-aqueous electrolytic solutionwas prepared using 1 wt. % of 2-butynylene bis(methanesulfonate) (acompound represented by the formula (III)) as the alkyne compound. Thecycle of charge and discharge was tested in the same manner as inExample 1. The results are shown below.

Initial discharging capacity (relative value):

1.00

Remaining rate of discharging capacity after 300 cycles:

81.4

Example 10

A cylindrical battery having the size of 18650 was prepared in the samemanner as in Example 1, except that a non-aqueous electrolytic solutionwas prepared using 1 wt. % of 2,4-hexadiynylene bis(methyl carbonate) (acompound represented by the formula (IV)) as the alkyne cornpound. Thecycle of charge and discharge was tested in the same manner as inExample 1. The results are shown below.

Initial discharging capacity (relative value):

1.00

Remaining rate of discharging capacity after 300 cycles:

80.3

Example 11

A cylindrical battery having the size of 18650 was prepared in the samemanner as in Example 1, except that a non-aqueous electrolytic solutionwas prepared using 0.5 wt. % of di(2-propynyl) carbonate (a compoundrepresented by the formula (V)) as the alkyne compound. The cycle ofcharge and discharge was tested in the same manner as in Example 1. Theresults are shown below.

Initial discharging capacity (relative value):

1.00

Remaining rate of discharging capacity after 300 cycles:

80.5

Example 12

A cylindrical battery having the size of 18650 was prepared in the samemanner as in Example 1, except that a non-aqueous electrolytic solutionwas prepared using 0.5 wt. % of di(2-propynyl)sulfite (a compoundrepresented by the formula (VI)) as the alkyne compound. The cycle ofcharge and discharge was tested in the same manner as in Example 1. Theresults are shown below.

Initial discharging capacity (relative value):

1.00

Remaining rate of discharging capacity after 300 cycles:

82.5

Example 13

A cylindrical battery having the size of 18650 was prepared in the samemanner as in Example 1, except that a non-aqueous electrolytic solutionwas prepared using 0.2 wt. % of di(2-propynyl)oxalate (a compoundrepresented by the formula (VI)) as the alkyne compound. The cycle ofcharge and discharge was tested in the same manner as in Example 1. Theresults are shown below.

Initial discharging capacity (relative value):

100

Remaining rate of discharging capacity after 300 cycles:

81.7

Example 14

A cylindrical battery having the size of 18650 was prepared in the samemanner as in Example 1, except that a non-aqueous electrolytic solutionwas prepared using 0.1 wt. % of phenylacetylene (a compound representedby the formula (VII)) as the alkyne compound. The cycle of charge anddischarge was tested in the same manner as in Example 1. The results areshown below.

Initial discharging capacity (relative value):

1.00

Remaining rate of discharging capacity after 300 cycles:

80.4

Example 15

A cylindrical battery having the size of 18650 was prepared in the samemanner as in Example 1, except that a non-aqueous electrolytic solutionwas prepared using 1 wt. % of 2-propynyl methanesulfonate (a compoundrepresented by the formula (II)) as the alkyne compound, and LiMn₂O₄ wasused as the positive electrode (active cathode material) in place ofLiCoO₂. The cycle of charge and discharge was tested in the same manneras in Example 1. The results are shown below.

Initial discharging capacity (relative value):

0.87

Remaining rate of discharging capacity after 300 cycles:

80.8

Example 16

A non-aqueous solvent of EC:DMC:DEC having a volume ratio of 30:20:50was prepared. In the solvent, LiPF₆ and LiN(SO₂CF₃)₂ were dissolved toprepare a solution of electrolyte salts having the concentrations of 0.9M and 0.1 M respectively. To the non-aqueous electrolytic solution, 1wt. % of 1,3-propanesultone (PS, based on the non-aqueous electrolyticsolution) and 2 wt. % of cyclohexylbenzene (CHB, based on thenon-aqueous electrolytic solution) were added. To the non-aqueouselectrolytic solution, 1 wt. % of 2-propynyl methyl carbonate (an alkynecompound represented by the formula (II), based on the non-aqueouselectrolytic solution) and 1 wt. % of vinylene carbonate (based on thenon-aqueous electrolytic solution) were further added as the additives.

A cylindrical battery having the size of 18650 was prepared in the samemanner as in Example 1, except that the above-prepared non-aqueouselectrolytic solution was used. The cycle of charge and discharge wastested in the same manner as in Example 1. The results are shown below.

Initial discharging capacity (relative value):

1.00

Remaining rate of discharging capacity after 300 cycles:

82.2

Example 17

A non-aqueous solvent of EC:DMC:DEC having a volume ratio of 30:20:50was prepared. In the solvent, LiPF₆ was dissolved to prepare a solutionof an electrolyte salt having the concentration of 1 M. To thenon-aqueous electrolytic solution, 0.5 wt. % of biphenyl (BP, based onthe non-aqueous electrolytic solution) and 2 wt. % of cyclohexylbenzene(CHB, based on the non-aqueous electrolytic solution) were added. To thenon-aqueous electrolytic solution, 0.5 wt. % of di(2-propynyl)sulfite(an alkyne compound represented by the formula (VI), based on thenon-aqueous electrolytic solution) and 1 wt. % of vinylene carbonate(based on the non-aqueous electrolytic solution) were further added asthe additives.

A cylindrical battery having the size of 18650 was prepared in the samemanner as in Example 1, except that the above-prepared non-aqueouselectrolytic solution was used. The cycle of charge and discharge wastested in the same manner as in Example 1. The results are shown below.

Initial discharging capacity (relative value):

100

Remaining rate of discharging capacity after 300 cycles:

81.1

Example 18

A non-aqueous solvent of EC:DMC:DEC having a volume ratio of 30:20:50was prepared. In the solvent, LiPF₆ was dissolved to prepare a solutionof an electrolyte salt having the concentration of 1 M. To thenon-aqueous electrolytic solution, 1 wt. % of tert-butylbenzene (TBB,based on the non-aqueous electrolytic solution) and 1 wt. % ofcyclohexylbenzene (CHB, based on the non-aqueous electrolytic solution)were added. To the non-aqueous electrolytic solution, 0.5 wt. % ofdi(2-propynyl)sulfite (an alkyne compound represented by the formula(VI), based on the non-aqueous electrolytic solution) and 1 wt. % ofvinylene carbonate (based on the non-aqueous electrolytic solution) werefurther added as the additives.

A cylindrical battery having the size of 18650 was prepared in the samemanner as in Example 1, except that the above-prepared non-aqueouselectrolytic solution was used. The cycle of charge and discharge wastested in the same manner as in Example 1. The results are shown below.

Initial discharging capacity (relative value):

1.00

Remaining rate of discharging capacity after 300 cycles:

81.4

Example 19

A non-aqueous solvent of EC:DMC:DEC having a volume ratio of 30:20:50was prepared. In the solvent, LiPF₆ was dissolved to prepare a solutionof an electrolyte salt having the concentration of 1 M. To thenon-aqueous electrolytic solution, 1 wt. % of tert-pentylbenzene (TPB,based on the non-aqueous electrolytic solution) and 1 wt. % ofcyclohexylbenzene (CHB, based on the non-aqueous electrolytic solution)were added. To the non-aqueous electrolytic solution, 0.5 wt. % ofdi(2-propynyl)sulfite (an alkyne compound represented by the formula(VI), based on the non-aqueous electrolytic solution) and 1 wt. % ofvinylene carbonate (based on the non-aqueous electrolytic solution) werefurther added as the additives.

A cylindrical battery having the size of 18650 was prepared in the samemanner as in Example 1, except that the above-prepared non-aqueouselectrolytic solution was used. The cycle of charge and discharge wastested in the same manner as in Example 1. The results are shown below.

Initial discharging capacity (relative value):

1.00

Remaining rate of discharging capacity after 300 cycles:

81.8

Example 20 Preparation of Non-Aqueous Electrolytic Solution

A non-aqueous solvent of EC:MEC having a volume ratio of 30:70 wasprepared. In the solvent, LiPF₆ was dissolved to prepare a 1 M solutionof an electrolyte salt. To the non-aqueous electrolytic solution, 0.3wt. % of di(2-propynyl)oxalate (an alkyne compound represented by theformula (VI), based on the non-aqueous electrolytic solution) was added.To the solution, 2 wt. % of vinylene carbonate (based on the non-aqueouselectrolytic solution) was further added. To the solution, 1 wt. % ofcyclohexylbenzene (CHB, based on the non-aqueous electrolytic solution)and 3 wt. % of 1-fluoro-4-cyclohexylbenzene (FCHB, based on thenon-aqueous electrolytic solution) were furthermore added.

(Preparation of Lithium Secondary Battery and Measurement of BatteryPerformance)

With 94 wt. % of LiCoO₂ (active cathode material), 3 wt. % of graphite(conductive material) and polyvinylidene fluoride (binder) were mixed.To the mixture, 1-methyl-2-pyrrolidone (solvent) was added. A surface ofaluminum foil was coated with the resulting solution. The mixture wasdried, molded under pressure, and heated to form a positive electrodecomposition layer (cathode).

With 95 wt. % of artificial graphite (active anode material) having agraphitic crystalline structure with a distance (d₀₀₂) of 0.335 nmbetween the lattice between lattice faces (002), 5 wt. % ofpolyvinylidene fluoride (binder) was mixed. To the mixture,1-methyl-2-pyrrolidone (solvent) was added. A surface of copper foil wascoated with the resulting solution. The mixture was dried, molded underpressure and heated to form a negative electrode composition layer(anode).

The positive electrode, the negative electrode and a separatorcomprising a micro porous polyethylene film (thickness: 20 μm) wereplaced in a battery vessel. The non-aqueous electrolytic solution waspoured into the battery. Carbon dioxide having the dew point of −60° C.was introduced into the battery, and the battery was sealed to prepare acylindrical battery having the size of 18650 (diameter: 18 mm, height:65 mm). A pressure-discharging opening and an inner current breaker (PTCelement) were attached to the battery. The positive electrodecomposition layer has the density of 3.5 g/cm³, and the negativeelectrode composition layer has the density of 1.6 g/cm³. The positiveelectrode composition layer has the thickness of 70 μm (per one surfaceof the collector), and the negative electrode composition layer has thethickness of 60 μm (per one surface of the collector).

The 18650 battery was charged with the constant current of 2.2 A (1C) ata high temperature (60° C.) to reach 4.2 V. The battery was furthercharged under the constant voltage for 3 hours in total to reach thefinal voltage of 4.2 V. The battery was discharged under the constantcurrent of 2.2 A (1C) to reach the final voltage of 3.0 V. The cycle ofcharge and discharge was repeated. The initial discharging capacity(mAh) was the substantially same (1.01) as the result using 1M ofLiPF₆-EC/PC/MEC (volume ratio: 30/5/65) containing no alkyne compound asthe non-aqueous electrolytic solution (Comparison Example 1 describedabove). The battery performance was measured after 300 cycles. Theremaining rate of the discharging capacity to the initial dischargingcapacity (100%) was 82.5%.

After the cycle test was repeated five times, the 18650 battery wasfully charged to reach 4.2V at the or dinary temperature (20° C.), andfurther charged with the constant current of 2.2 A (1C) for 2 hours toconduct an excessive charge test. The temperature on the surface of thebattery was lower than 120° C., which is the standard highesttemperature for safety.

Example 21

A cylindrical battery having the size of 18650 was prepared in the samemanner as in Example 20, except that a non-aqueous electrolytic solutionwas prepared using 4 wt. % of fluorobenzene (FB) in place of1-fluoro-4-cyclohexylbenzene (FCHB) as the additive. The cycle test ofcharge and discharge and the excessive charge test were conducted in thesame manner as in Example 20. The results are shown below.

Initial discharging capacity (relative value):

1.01

Remaining rate of discharging capacity after 300 cycles:

82.1

Surface temperature of battery in excessive charge test: lower than 120°C.

Example 22

A cylindrical battery having the size of 18650 was prepared in the samemanner as in Example 20, except that a non-aqueous electrolytic solutionwas prepared using 1 wt. % of 1-fluoro-4-cyclohexylbenzene (FCHB) and 4wt. % of fluorobenzene (FB) in place of cyclohexylbenzene (CHB) as theadditives. The cycle test of charge and discharge and the excessivecharge test were conducted in the same manner as in Example 20. Theresults are shown below.

Initial discharging capacity (relative value):

1.01

Remaining rate of discharging capacity after 300 cycles:

82.2

Surface temperature of battery in excessive charge test:

lower than 120° C.

Example 23

A cylindrical battery having the size of 18650 was prepared in the samemanner as in Example 20, except that a non-aqueous electrolytic solutionwas prepared using 1.5 wt. % of cyclohexylbenzene (CHB) and 1 wt. % of2,4-difluoroanisole (DFA) in place of 1-fluoro-4-cyclohexylbenzene(FCHB) as the additives. The cycle test of charge and discharge and theexcessive charge test were conducted in the same manner as in Example20. The results are shown below.

Initial discharging capacity (relative value):

1.01

Remaining rate of discharging capacity after 300 cycles:

81.5

Surface temperature of battery in excessive charge test: lower than 120°C.

Example 24

A cylindrical battery having the size of 18650 was prepared in the samemanner as in Example 20, except that a non-aqueous electrolytic solutionwas prepared using 2 wt. % of 1-fluoro-4-cyclohexylbenzene (FCHB) and 1wt. % of 2,4-difluoroanisole (DFA) in place of cyclohexylbenzene (CHB)as the additives. The cycle test of charge and discharge and theexcessive charge test were conducted in the same manner as in Example20. The results are shown below.

Initial discharging capacity (relative value):

1.01

Remaining rate of discharging capacity after 300 cycles:

81.9

Surface temperature of battery in excessive charge test: lower than 120°C.

Example 25

A cylindrical battery having the size of 18650 was prepared in the samemanner as in Example 20, except that a non-aqueous electrolytic solutionwas prepared using 0.4 wt. % of ethylene sulfite (ES) in addition todi(2-propynyl)oxalate (an alkyne compound represented by the formula(VI)), vinylene carbonate (VC), cyclohexylbenzene (CHB) and1-fluoro-4-cyclohexylbenzene (FCHB) as the additives. The cycle test ofcharge and discharge and the excessive charge test were conducted in thesame manner as in Example 20. The results are shown below.

Initial discharging capacity (relative value):

1.01

Remaining rate of discharging capacity after 300 cycles:

82.6

Surface temperature of battery in excessive charge test: lower than 120°C.

Example 26

A cylindrical battery having the size of 18650 was prepared in the samemanner as in Example 20, except that a non-aqueous electrolytic solutionwas prepared using 0.3 wt. % of di(2-propynyl)oxalate, 0.3 wt. % ofdi(2-propynyl)sulfite, 2 wt. % of vinylene carbonate (VC), 1 wt. % oftert-pentylbenzene (TPB) and 3 wt. % of 1-fluoro-4-cyclohexylbenzene(FCHB) as the additives. The cycle test of charge and discharge and theexcessive charge test were conducted in the same manner as in Example20. The results are shown below.

Initial discharging capacity (relative value):

1.01

Remaining rate of discharging capacity after 300 cycles:

83.2

Surface temperature of battery in excessive charge test:

lower than 120° C.

Example 27

A non-aqueous solvent of EC:PC:DMC:DEC having a volume ratio of30:5:15:50 was prepared. In the solvent, LiPF₆ was dissolved to preparea 1 M solution of an electrolyte salt. To the non-aqueous electrolyticsolution, 0.5 wt. % of 2-propynyl formate (an alkyne compoundrepresented by the formula (II), based on the non-aqueous electrolyticsolution) and 2 wt. % of vinylene carbonate (based on the non-aqueouselectrolytic solution) was added.

A cylindrical battery having the size of 18650 was prepared in the samemanner as in Example 20, except that the non-aqueous electrolyticsolution was used. The cycle test of charge and discharge and theexcessive charge test were conducted in the same manner as in Example20. The results are shown below.

Initial discharging capacity (relative value):

1.00

Remaining rate of discharging capacity after 300 cycles:

82.4

Surface temperature of battery in excessive charge test: lower than 120°C.

Example 28

A cylindrical battery having the size of 18650 was prepared in the samemanner as in Example 27, except that a non-aqueous electrolytic solutionwas prepared using 0.5 wt. % of 2-butynylene diformate (a compoundrepresented by the formula (III)). The cycle test of charge anddischarge and the excessive charge test were conducted in the samemanner as in Example 20. The results are shown below.

Initial discharging capacity (relative value):

1.00

Remaining rate of discharging capacity after 300 cycles:

82.0

Surface temperature of battery in excessive charge test: lower than 120°C.

Example 29

A cylindrical battery having the size of 18650 was prepared in the samemanner as in Example 27, except that a non-aqueous electrolytic solutionwas prepared using 0.5 wt. % of 2,4-hexadiynylene diformate (a compoundrepresented by the formula (IV)). The cycle test of charge and dischargeand the excessive charge test were conducted in the same manner as inExample 20. The results are shown below.

Initial discharging capacity (relative value):

1.00

Remaining rate of discharging capacity after 300 cycles:

81.4

Surface temperature of battery in excessive charge test:

lower than 120° C.

1. A non-aqueous electrolytic solution comprising an electrolyte salt ina non-aqueous solvent which comprises a cyclic carbonate selected fromthe group consisting of ethylene carbonate and propylene carbonate and achain carbonate for a lithium secondary battery, wherein the non-aqueouselectrolytic solution further contains a vinylene carbonate compoundrepresented by the formula (I) in an amount of 0.05 to 5 wt. %, and atleast one alkyne compound represented by the formula (III), (IV), or(VI) in an amount of 0.1 to 3 wt. %:

in which each of R¹ and R² independently is a hydrogen atom or an alkylgroup having 1 to 4 carbon atoms;

in which each of R⁶ to R⁹ independently is a hydrogen atom, an alkylgroup having 1 to 12 carbon atoms, a cycloalkyl group having 3 to 6carbon atoms, or an aryl group having 6 to 12 carbon atoms, or R⁶ and R⁷or R⁸ and R⁹ are combined with each other to form a cycloalkylene grouphaving 3 to 6 carbon atoms; x is 1 or 2; Y² is —COOR²¹, —COR²¹, or—SO₂R²¹, wherein R²¹ is a hydrogen atom, an alkyl group having 1 to 12carbon atoms, a cycloalkyl group having 3 to 6 carbon atoms, or an arylgroup having 6 to 12 carbon atoms; and Y³ is —COOR²², —COR²², or—SO₂R²², wherein R²² is a hydrogen atom, an alkyl group having 1 to 12carbon atoms, a cycloalkyl group having 3 to 6 carbon atoms, or an arylgroup having 6 to 12 carbon atoms;

in which each of R¹⁰ to R¹³ independently is a hydrogen atom, an alkylgroup having 1 to 12 carbon atoms, a cycloalkyl group having 3 to 6carbon atoms, or an aryl group having 6 to 12 carbon atoms, or R¹⁰ andR¹¹ or R¹² and R¹³ are combined with each other to form a cycloalkylenegroup having 3 to 6 carbon atoms; x is 1 or 2; Y⁴ is —COOR²³, —COR²³, or—SO₂R²³, wherein R²³ is a hydrogen atom, an alkyl group having 1 to 12carbon atoms, a cycloalkyl group having 3 to 6 carbon atoms, or an arylgroup having 6 to 12 carbon atoms; and Y⁵ is —COOR²⁴, —COR²⁴, or—SO₂R²⁴, wherein R²⁴ is a hydrogen atom, an alkyl group having 1 to 12carbon atoms, a cycloalkyl group having 3 to 6 carbon atoms, or an arylgroup having 6 to 12 carbon atoms;

in which each of R²⁵ to R²⁷ independently is a hydrogen atom, an alkylgroup having 1 to 12 carbon atoms, a cycloalkyl group having 3 to 6carbon atoms, an aryl group having 6 to 12 carbon atoms, or an aralkylgroup having 7 to 12 carbon atoms, or R²⁶ and R²⁷ are combined with eachother to form a cycloalkylene group having 3 to 6 carbon atoms; x is 1or 2; W is sulfinyl, sulfonyl, or oxalyl; and Y⁶ is an alkyl grouphaving 1 to 12 carbon atoms, an alkenyl group having 2 to 12 carbonatoms, an alkynyl group having 2 to 12 carbon atoms, a cycloalkyl grouphaving 3 to 6 carbon atoms, an aryl group having 6 to 12 carbon atoms,or an aralkyl group having 7 to 12 carbon atoms.
 2. The non-aqueouselectrolytic solution of claim 1, wherein the non-aqueous electrolyticsolution contains the vinylene carbonate compound in an amount of 0.1 to3 wt. %.
 3. The non-aqueous electrolytic solution of claim 1, whereinthe vinylene carbonate compound is vinylene carbonate.
 4. Thenon-aqueous electrolytic solution of claim 1, wherein the alkynecompound is 2-butynylene bis(methyl carbonate), 2-butynylenebis(methanesulfonate), 2,4-hexadiynylene bis(methyl carbonate),di(2-propynyl)sulfite, di(2-propynyl)oxalate, ethyl 2-propynyl oxalate,2-butynylene diformate or 2,4-hexadiynylene diformate.
 5. Thenon-aqueous electrolytic solution of claim 1, wherein the non-aqueouselectrolytic solution further contains an aromatic compound in an amountof 0.1 to 5 wt. %, said aromatic compound being selected from the groupconsisting of cyclohexylbenzene, a fluorocyclohexylbenzene compound,biphenyl, terphenyl, diphenyl ether, 2-fluorophenyl phenyl ether,4-fluorophenyl phenyl ether, fluorobenzene, difluorobenzene,2-fluorobiphenyl, 4-fluorobiphenyl, 2,4-difluoroanisole,tert-butylbenzene, 1,3-di-tert-butylbenzene,1-fluoro-4-tert-butylbenzene, tert-pentylbenzene, tert-butyl biphenyl,tert-pentyl biphenyl, a partially hydrogenated o-terphenyl, a partiallyhydrogenated m-terphenyl and a partially hydrogenated p-terphenyl. 6.The non-aqueous electrolytic solution of claim 1, wherein thenon-aqueous electrolytic solution further contains a mixture having aweight ratio of 50:50 to 10:90 in a total amount of 0.1 to 5 wt. %, saidmixture being selected from the group consisting of a mixture ofbiphenyl and cyclohexylbenzene, a mixture of cyclohexylbenzene andtertbutylbenzene, a mixture of cyclohexylbenzene and tert-pentylbenzene,a mixture of biphenyl and fluorobenzene, a mixture of cyclohexylbenzeneand fluorobenzene, a mixture of 2,4-difluoroanisole andcyclohexylbenzene, a mixture of cyclohexylbenzene and1-fluoro-4-tertbutylbenzene, a mixture of cyclohexylbenzene and afluorocyclohexylbenzene compound, a mixture of a fluorocyclohexylbenzenecompound and fluorobenzene, and a mixture of 2,4-difluoroanisole and afluorocyclohexylbenzene compound.